Typical unmanned aerial vehicles (UAVs) are less than 15 cm with wingspan. In traditional winged MAVs, the control surfaces are open to the wind and thus very sensitive to wind gusts, at speeds comparable to vehicle flight speeds.
The traditional lift generation mechanism in a micro air vehicle (MAV), is shown in FIG. 1A. Referring to the top of FIG. 1A, air moves over the wing surface with no separation such that the conventional airfoil produces a steady state standing vortex trailing the wing. This vortex does not effect lift generation by the wing. As shown at the bottom of FIG. 1A, flapping wings, can generate a vortex tube with each stroke to produce lift. Referring to the bottom portion of FIG. 1A, a bound vortex is formed after each stroke of the flapping wing pair, where two bound vortexes are shown in FIG. 1A. The bound vortexes create a three-dimensional wake structure that can be considered as a vortex tube. The bound vortex formed after each stroke is the source of lift for the flapping wing pair. The magnitude of this lift force is, however, unsteady. The nature of the magnitude of the lift force produced by the vortex tube resulting from flapping wings is plotted in FIG. 1B. While the flapping wing theoretically mimics insects and birds in nature, the lift generated due to rigid flapping wings may be easily disrupted with the rupture of this vortex tubes at moderate wind gusts. The disruption of the lift caused by the rupture of the vortex tube results in a serious limitation to the hovering capability of a MAV using a flapping rigid wing. The main difference between flapping flight and airfoil flight is the continued formation and shedding of the wing vortex in flapping flight.
There has been a significant experimental and theoretical effort in the area of magnetohydrodynamics (MHD) control of high-speed air flows. The effects of external magnetic field on plasmas have been investigated for flow control purposes. Beyond the first computational demonstration by Bush (1958), Zimmer (1969) showed that a strong magnetic field and plasma altered the standoff distance of a bow shock in front of a hemispherical body by a factor of 7.5. More recently, investigators (Menart et al.) have shown that a magnetic field in combination with plasma does alter the flow field. The precise mechanism though, is still unclear.
Electric body forces produced by a radio frequency (rf) induced surface dielectric barrier discharge (DBD) can be employed for low-speed flow control. One such application is to re-attach separated flows through induced wall-jet (Roth, 2003; Corke et al, 2005; Roy and Gaitonde, 2005; Gaitonde et al. 2006).
There exists a need in the art for a MAV that is less sensitive to wind gusts than traditional winged MAV's.